A survivorship curve can indicate how long individuals survive in a population, or all members of the same species on one region. The curves come in three distinct types. In a Type I curve, the young have a high survival rate and typically live a long life. An example of this curve can be seen in the Daal sheep that live in Mt. Denali National Park in Alaska. Humans are also an example of a Type I curve. In a Type II curve, individuals have a relatively constant death rate throughout their life span. An example of this curve can be found in populations of American robins. A Type III curve includes those species that have a large number of young—most of which die at a high rate, at an early age—but have a lower death rate at later ages. An example of this survivorship curve can be found in lobsters and crabs.